This invention relates generally to power door operators for multi-passenger mass transit vehicles, more particularly to an overhead electrically driven door operator mounted for opening and closing dual leaf swing doors such as used in multiple passenger vehicles including, airport utility transports, school, and small transit buses.
Operators of the type disclosed herein are at present largely pneumatically actuated since in most large vehicles use of air brake systems provides a reliable and convenient source of operating air at controlled pressures. However, the vehicles described above incorporate hydraulic brake systems. Therefore, no air supply is available, and hydraulic door drives are high in cost and involve excessive maintenance in order to prevent leaks and loss of brake system integrity. A growing need for a reliable low cost electric bus door operator now exists.
An electric operator for transit vehicles disclosed in U.S. Pat. No. 4,375,140, the specification of which is hereby incorporated by reference. While presenting a required alternate approach to door equipment for certain vehicles, operators of the type disclosed in U.S. Pat. No. 4,375,140 have substantial shortcomings, including, among others, limited force for holding a door closed, lack of provision for controlling individual door leaf phasing (i.e., opening/closing relationship) in operation, and an attendant lack of adjustment of the hold-closed force. Further, the emergency release clutch employed is automatically reset on subsequent powered operation, and utilizes an actuating lever having a substantial protrusion into the passenger space.
The operator disclosed herein overcomes many of these problems through provision of adjustable length door drive lever arms, and an emergency door opening clutch having an actuating plunger incorporating improved and ergonometrically correct actuation. The clutch actuating plunger greatly reduces protrusion into passenger space.